I haven't had a lot of success catching largemouth on subsurface flies. Most of my success is on top. I fish deer hair, balsa, and foam flies, but deer hair is my favorite and what I've had the most success with. I fish deer hair poppers, divers, and sliders, they all work for me. I probably do best with rabbit strip tails, although feather/maribou/hair tails do OK too. I use TMC 8089 hooks in size 6 and 2; the size 2 is a pretty large hook, similar to 2/0 and larger in other brands. As for colors, white belly with green/olive back, with some black and /or yellow, is my most common combination. All my flies have weedguards (single strand of 20# Mason hard mono), I don't think I could fish effectively without them because I cast right into weed and other cover,over logs,etc and pull flies through/over the cover. I also cast flies on to the shore, or onto boat docks, and pull the flies so they drop in the water. Gotta have the weedgaurd, and haven't noticed/felt like I lose any fish because of them.

Man i just wish I could get out and use a few right now!!!
When I do I'll use Clouser's 01's in grey and white mostly. A few other colors work to. Black and white decievers and big bellyache minnow pattern color based on water clarity.
I'll add black poppers and big hoppers for those dog days of summer, when things start to cool off it's big mouse patterns and clousers again.

I left the range open but I would have thought a deer hair bug would have been more popular. The Clouser minnow in white and chartreuse(or gray) seems very popular. How deep an area can you fish with them and what type of a retrieve?

If I could only fish one fly for bass, it would be an Arizona Simiseal Leech. I have used this pattern from early spring through late fall with great success. That being said, my favorite way to catch bass is fishing top water deerhair poppers and divers. Unfortunately, there is a fairly narrow window here in the PNW where the water temperatures are right for that type of fishing.

I also like to fish a Polar Fibre Clouser Minnow for all types of fish. In the early season, I will fish this pattern deep using a type VI sinking line. Once the fly is at the desired depth, I usually fish it using a jerk, jerk, strip retreive. The bass usually strike the fly right after the strip. Once the waters warm up and the bass move towards the shallows, I will use a floating line.

Clouser minnow(white/red), hand cut foam poppers,and my personal fav is my very own muppet mullet which is a cone headed jig with rust orange dubbing,and a rabbit strip tail. Plus some soft black hackle. Minnows are great in both streams and lakes and the poppers and mullet are always a winner in early morning and evenings at the lake